Molecular communication channels transmit information by the release and detection of chemical substances. Single information bits can be encoded as individual releases of certain amounts of molecules. Intersymbol interference between successive releases can be minimized by enforcing a decay of the substrate concentration through enzyme reactions. A model for the short term behaviour of the enzyme kinetics is employed to derive the achievable symbol transmission rate in terms of the parameters of the enzyme reaction and the sensitivity of the substrate receptor. The resulting relation facilitates the design of the biochemical environment for efficient molecular communication.